GB/T 3078-2019 PDF EnglishUS$135.00 · In stock · Download in 9 seconds
GB/T 3078-2019: Quality structural steel cold drawn bars Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 3078: Historical versions
GB/T 3078-2019: Quality structural steel cold drawn bars---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT3078-2019NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 77.140.60 H 44 Replacing GB/T 3078-2008 Quality structural steel cold drawn bars Issued on. AUGUST 30, 2019 Implemented on. JULY 01, 2020 Issued by. State Administration for Market Regulation; Standardization Administration of the People’s Republic of China. Table of ContentsForeword... 3 1 Scope... 4 2 Normative references... 4 3 Terms and definitions... 5 4 Classification... 6 5 Order content... 6 6 Size, shape and allowable deviation... 7 7 Technical requirements... 7 8 Test method... 12 9 Inspection rules... 14 10 Packaging, marking and quality certificate... 151 ScopeThis Standard specifies the classification, ordering content, size, shape and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and quality certificates of structural steel cold drawing and cold drawing polish steels. This Standard applies to quality carbon structural steel and alloy structural steel cold drawing bars (round steel, square steel and hexagonal steel) and cold drawing polish round steel (hereinafter collectively referred to as "steel").2 Normative referencesThe following documents are indispensable for the application of this document. For dated references, only the dated version applies to this document. For undated references, the latest edition (including all amendments) applies to this document. GB/T 222, Permissible tolerances for chemical composition of steel products GB/T 224, Determination of depth of decarburization of steels GB/T 225, Steel - Hardenability test by end quenching (Jominy test) GB/T 226, Test method for macrostructure and defect of steel by etching GB/T 228.1, Metallic materials. Tensile testing. Part 1.Method of test at room temperature GB/T 229, Metallic materials. Charpy pendulum impact test method GB/T 231.1, Metallic materials. Brinell hardness test. Part 1.Test method GB/T 341-2008, Steel wire - Classification and terminology GB/T 699, Quality carbon structural steels GB/T 905-1994, Dimension, shape, weight and tolerance for cold-drawn round, square and hexagonal steels GB/T 1814, Inspection method for steel work fractures GB/T 1979, STANDARD diagrams for macrostructure and defect of structural steels3 Terms and definitionsTerms and definitions determined by GB/T 341-2008 and GB/T 3207-2008 are applicable to this document. For ease of use, some of the terms and definitions in GB/T 341-2008 and GB/T 3207-2008 are repeated below. 3.1 Cold drawing A process in which it is formed by pressure processing methods such as die drawing or roll drawing at normal temperature. 3.2 Polish steel Polished round steel after drawing or peeling.4 ClassificationSteels, according to the use and processing purposes, are divided into.5 Order contentContracts which are ordered under this Standard shall include the following contents. a) number of this Standard; b) product name; c) designation or unified digital code of the steel; d) delivery weight (or quantity); e) size, shape and allowable deviation (see Chapter 6); f) use and processing purposes (when it is not specified, perform according to steel for cutting); g) delivery state (see 7.3.1);6 Size, shape and allowable deviation6.1 The size, shape and allowable deviation of cold drawing steel bars shall comply with the provisions of GB/T 905-1994.The specific requirements shall be indicated in the contract. 6.2 The size, shape and allowable deviation of cold drawing polish round steel shall comply with the provisions of GB/T 3207-2008.The specific requirements shall be indicated in the contract.7 Technical requirements7.1 Designation and chemical composition 7.1.1 For the steel designation and chemical composition, quality carbon structural steel shall comply with the provisions of GB/T 699, alloy structural steel shall comply with the provisions of GB/T 3077.According to the requirements of the buyer, it can be ordered according to other designations if it is specified in the contract. 7.1.2 The allowable deviation of chemical composition of the finished steel product shall comply with the provisions of GB/T 222. 7.2 Smelting method Unless otherwise specified in the contract, the smelting method is chosen by the supplier. 7.3 Delivery state 7.3.1 The delivery state of steels is shown in Table 1.The specific delivery state shall be indicated in the contract. If it is not specified, deliver in cold drawing state. 7.4 Hardness 7.4.1 The delivery hardness value of steels (except for normalizing state) shall comply with the requirements of Table 2.According to the requirements of the buyer, the hardness value of the alloy structural steel that is delivered under heat treatment after cold drawing (except for normalizing state) without designation in Table 2 shall comply with the provisions of GB/T 3077; the hardness of the steel that is delivered under cold drawing and cold drawing polish state shall not be greater than 285 HBW. 7.4.2 For the steel for hot-press processing that is delivered in the cold drawing state, the Brinell hardness values of 50Mn2, 35CrMnSi, 42CrMo and 35CrMoV steels shall comply with the requirements of Table 2; 7.4.3 For steels whose cross-section nominal size (diameter, thickness or diagonal length) is less than 5 mm, do not perform the hardness test. If it is required by the buyer and stated in the contract, the tensile strength can be used instead of the hardness. The specific requirements are determined by the supplier and the buyer. 7.5 Mechanical property If it is required by the buyer and stated in the contract, it's available to test the mechanical properties of the steel in the delivery state; its mechanical properties shall meet the requirements of Table 3.The mechanical properties of the steel in the delivery state, whose designation is not listed in Table 3, are determined by negotiation between the supplier and the buyer. 7.6 Forging The steel for forging shall be subjected to a forging test; it shall be indicated in the contract whether it’s cold or hot forging. For cold forging test, forge to one- half of the original height of the sample; for hot forging test, forge to one-third of the original height of the sample. The surface of the sample after forging shall not have visible cracks. 7.7 Macrostructure 7.7.1 The macrostructure of quality carbon structural steel shall comply with the provisions of GB/T 699. 7.7.2 The macrostructure of alloy structural steel shall comply with the provisions of GB/T 3077. 7.8 Decarburization layer According to the requirements of the buyer, the steel whose carbon content is not less than 0.30% can be decarburized, and the one-side total decarburization layer (ferrite + transition layer) depth shall meet the requirements of Table 4. 7.9 Surface quality 7.9.1 The surface of the steel shall be clean, smooth, free of cracks, folds, crusting, inclusions, cracks and scale cinders; the surface of the heat-treated cold drawing steel is allowed to have an oxidized color. 7.9.2 For steels for cutting, the surface is allowed to have pitting, scratches, drawing stamps, black spots, concave surfaces, cleaning slopes and lubricant marks, whose depth does not exceed the nominal size tolerance from the nominal size, and some individual hairlines whose depth is half the tolerance. 7.10 Special requirements. According to the requirements of the buyer, if it is negotiated between the supplier and the buyer, and specified in the contract, steels of the following special requirements can be supplied. a) reduce the chemical composition range; b) impact absorption energy of the steel in the delivery state; c) specify upper and lower limits of mechanical properties; d) inspect the layered fracture; e) inspect the banded structure; f) inspect the grain size;8 Test methodThe inspection items and test methods of each batch of steels shall comply with the requirements of Table 6.9 Inspection rules9.1 Inspection and acceptance 9.1.1 The delivery inspection and acceptance of steels shall be carried out by the supplier's quality and technical supervision department. 9.2 Batch rules the steels shall be inspected and accepted in batches. Each batch shall consist of steels of the same designation, the same heat number, the same processing method, the same size, the same delivery state, and the same heat treatment system (heating). 9.3 Sampling quantity and sampling portion The sampling quantity and sampling portion of the steels shall comply with the requirements of Table 6. 9.4 Re-inspection and determination rules 9.4.1 The re-inspection and determination rules of the steels shall comply with the provisions of GB/T 17505. 9.4.2 If the supplier can ensure that the steel is qualified, for the test results of the mechanical properties, macrostructure and non-metallic inclusions of steels or steel billet of the same heat number, it is allowed to replace the steel with billet, and replace the small one with the large one. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. |
